Remove stale spellcheck markers at idle time

third_party/WebKit/Source/core/editing/spellcheck/SpellChecker.cpp

Index: third_party/WebKit/Source/core/editing/spellcheck/SpellChecker.cpp
diff --git a/third_party/WebKit/Source/core/editing/spellcheck/SpellChecker.cpp b/third_party/WebKit/Source/core/editing/spellcheck/SpellChecker.cpp
index e26740a836c32da813eb5152f1c4237bccd5ca4b..cab9e399e8084c8146908c0d7f038e8de8e10da3 100644
--- a/third_party/WebKit/Source/core/editing/spellcheck/SpellChecker.cpp
+++ b/third_party/WebKit/Source/core/editing/spellcheck/SpellChecker.cpp
@@ -654,6 +654,9 @@ void SpellChecker::markAndReplaceFor(
 
 void SpellChecker::updateMarkersForWordsAffectedByEditing(
     bool doNotRemoveIfSelectionAtWordBoundary) {
+  if (RuntimeEnabledFeatures::idleTimeSpellCheckingEnabled())

[yosin_UTC9, 2017/04/05 01:52:35]

Nice! (^_^)b

+    return;
+
   DCHECK(frame().selection().isAvailable());
   TRACE_EVENT0("blink", "SpellChecker::updateMarkersForWordsAffectedByEditing");
   // TODO(editing-dev): We should hoist